Torque wrench equipped with a tightening angle measurement sensor

Abstract

Torque wrench provided with a tightening angle measurement sensor comprising a body ( 11 ), containing control circuits and an electronic processing unit having a handle ( 12 ) at one end for gripping by an operator who performs the tightening, and an arm ( 13 ) at the other end, said arm, at its free end, comprises a seat ( 16 ) in which there are alternatively engageable a plurality of inserts suitable for engaging the tool with a corresponding type and/or size of a mechanical member on which the tool is intended to act to perform a tightening operation, there being a gyroscope for measuring the tightening angle on said arm. The electronic processing unit of the wrench of means for compensating for deviations in the value of the received angle signal of the gyroscope, based on a compensation algorithm that corrects the value of the zero angle signal received from the gyroscope.

1 . Torque wrench equipped with a tightening angle measurement sensor comprising
 a body ( 11 ), containing control circuits and an electronic processing unit having at one end a handle ( 12 ) for gripping an operator who performs the tightening, and at the other end an arm ( 13 ),   said arm at its free end comprises a seat ( 16 ) in which a plurality of inserts suitable for engaging the tool with a corresponding type and/or size of a mechanical member on which the tool is intended to act can be alternatively engaged perform a tightening operation,   on this arm there is a gyroscope for measuring the tightening angle,   
       characterized in that the electronic processing unit of the torque comprises means to compensate for the deviations of the value of the received angle signal of the gyroscope, based on a compensation algorithm that corrects the value of the zero angle signal received from the gyroscope. 
     
     
         2 . Torque according to  claim 1  wherein said means comprise a table of correspondence between temperature and true zero angle signal provided by the gyroscope, stored in said processing unit and obtained during a torque calibration phase, in which the torque is subjected to temperature variations starting from a minimum value up to a maximum and during this period the angle signal is detected. 
     
     
         3 . Torque according to  claim 2  in which the table can also be obtained or corrected by self-learning, since the torque is equipped with a temperature sensor and therefore can correct the table as it detects new values, during normal use different from those initially set. 
     
     
         4 . Torque according to  claim 3 , in which in said table the deviation between the real zero signal received and the theoretical one is stored for predetermined temperature values. 
     
     
         5 . Torque according to  claim 3 , wherein said means during the step of tightening the torque at a measured temperature compensates the measured angle value with the offset value stored in said table for that measured temperature. 
     
     
         6 . Torque according to  claim 1 , wherein said means monitor cyclically, at successive predetermined instants (instant i, i+1, i+2 . . . ) the zero signal of the gyroscope itself and against a predetermined number of detected deviations of this signal with respect to the one previously detected above a predetermined threshold, reposition the zero of the gyroscope in correspondence with the last detected value. 
     
     
         7 . Torque according to  claim 6 , in which a counter is incremented at each increment of the received signal and the same counter is decremented at each decrement of the received signal, when said counter exceeds this predetermined positive or negative threshold of the last value detected by the gyroscope the value corresponding to zero degrees of rotation of the gyroscope is considered and the counter is reset. 
     
     
         8 . Torque according to  claim 1 , further comprising a temperature sensor. 
     
     
         9 . A method for compensating the deviations in the angle signal measured by a gyroscope integrated in a torque wrench when that torque wrench is active and at rest, this method comprising the following steps:
 a calibration phase in which the torque is subjected to temperature variations starting from a minimum value up to a maximum and during this period the angle signal, which corresponds to the zero angle value, is detected by the gyroscope, and in which the memorized a correspondence table between measured angle values and the detected temperature,   a tightening phase carried out with this torque in which the torque rotates and the signal stored in this table is subtracted from the value of the angle signal received instant by instant during rotation by the gyroscope at the current temperature measured by the temperature sensor of the torque or gyroscope.   
     
     
         10 . A method for compensating the deviations in the angle signal measured by a gyroscope integrated in a torque wrench which includes the cyclic repetition of the following steps until that torque wrench is active and at rest:
 receiving at predetermined instants an angle signal from the active gyroscope which corresponds instant by instant to the zero angle signal,   when an increase in the received angle signal value is greater than a pre-set increment threshold, increment a counter and when a decrement of the received angle signal value is greater than a pre-set decrement threshold, decrement the same counter,   if the counter exceeds a positive upper limit or a negative lower limit, the previously stored offset is increased which will be added or subtracted from the last detected value and reset the value of the counter.